This invention is directed to a quick cooling cryostat which employs Simon cooling in cooperation with Joule Thomson cooling.
Simon cooling occurs in a high pressure gas tank when gas is discharged from the tank. The remaining gas in the tank does work on the gas being expelled, to decrease the temperature of the gas remaining in the tank. R. W. Stuart, U.S. Pat. No. 3,593,537 describes a Simon cooler.
A Joule Thomson cooler is one where a pre-cooled gas is expanded out of a nozzle at the cold point and the cold exhaust gas passes over the incoming higher pressure gas to provide the precooling. An example of a Joule Thomson cryostat is shown in J. S. Buller et al., U.S. Pat. No. 3,640,091.
In the prior art, high pressure gas bottles have been used to supply refrigerant gas to a Joule Thomson cryostat, as in Wurtz U.S. Pat. No. 3,095,711, but the advantage of employing both cooling methods in combination only occurs for quick cooldown situations where the structures are close-coupled.